Man-made structures fragment habitat, constrain productivity and can prevent completion of the salmon’s lifecycle. Rivers that are impacted by manmade barriers are less resilient than those that flow naturally. Any barrier, small or large, will affect the rivers’ ability to support a natural and sustainable ecosystem. Installing or retaining barriers prevents natural functions such as sediment and gravel movements, cleansing of substrates and the movement of aquatic species through the system.
Adult Atlantic salmon can be compromised by structures with poorly designed or non-existent fish passes, including road culverts. Upstream fish migration for adult fish can be completely impeded or fish can be delayed by such structures. Delays to fish migration can expose fish to injury, which can lead to subsequent fish health issues. Such delays can also lead to increased pressure from predation and illegal exploitation.
Atlantic salmon downstream migration can be impeded by small and large-scale hydro generating schemes, weirs and other obstructions. Where free passage of fish is impeded, such barriers can expose salmon to increased predation pressure. In recent years this has been identified as a significant issue at a number of large impoundments, and we are working with SEPA to prioritise action to address these issues.
What are we doing?
Abstractions and impoundments are regulated by SEPA through the The Water Environment (Controlled Activities) (Scotland) Regulations 2011 (CAR), and these should require measures to ensure the free passage of fish. Fisheries Management Scotland are members of SEPA’s Fish and Fisheries Advisory Group and fish passage is a key issue for discussion and action, as it has been identified as one of the major impacts on Scottish rivers through the River Basin Management Planning process. SEPA have a programme of barrier removals which is funded by the Water Environment Fund. In addition, Fisheries Management Scotland members have been contributing to a prioritisation process to address issues of downstream fish passage at large impoundments. We are pushing for SEPA to use their regulatory powers to address these issues as soon as possible.